Ozzie,
Yours is exactly the type of info what I was hoping to learn. Thank you!
We do a lot of heavy FEL work, and keep the tires overinflated. Sidewall max calls for 18psi, and we use 25psi because it helps firm up the squishy ag tires. The tractor has never been ran over stumps, rocks, curbs, or potholes, and very seldom roaded.
FYI, Kubota is replacing the 2 front rims under warranty.
Haven't looked inside the wheels, but judging from the outside, they are a leak waiting to happen. The spokes appear to be riveted to the rims, which (it seems to me) are bound to loosen or cause cracking. Perhaps the rivets are welded inside the rims, which would be an improvement, but still a source for cracks to form.
Thanks again Ozzie!